1. Field of the Invention
The present invention relates to a magnetic recording and reproduction apparatus for performing recording and reproduction of signals to or from a magnetic tape which is wound around a rotation head cylinder of the magnetic recording and reproduction apparatus.
2. Description of the Related Art
FIG. 11 is a plan view of a conventional magnetic recording and reproduction apparatus 100. As shown in. FIG. 11, the magnetic recording and reproduction apparatus 100 includes a substrate 1 and a rotation head cylinder 2 attached to a cylinder attachment section 3 of the substrate 1.
FIG. 12 is a plan view of the substrate 1. The substrate 1 has a first through-hole 4 having a diameter C1, a second through-hole 5 having a diameter C2, a first positioning pin 6 having a diameter D1 and pressure-inserted into the substrate 1, and a second positioning pin 7 having a diameter D2 and pressure-inserted into the substrate 1.
FIG. 13 is a bottom view of the rotation head cylinder 2. The cylinder 2 has a first female screw 8, a second female screw 9, a first positioning hole 10 and a second positioning hole 11. The first positioning hole 10 is circular and has a diameter E1. The second positioning hole is substantially slot-shaped and has a width E2.
FIG. 16 is a cross-sectional view of the conventional magnetic recording and reproduction apparatus 100 taken along line Hxe2x80x94H in FIG. 11. As shown in FIG. 16, the rotation head cylinder 2 is attached to the substrate 1 via a first attaching screw 22 inserted Into the through-hole 4 of the substrate 1 and a second attaching screw 25 inserted into the through-hole 5 of the substrate 1.
FIG. 14 is a side view of the first attaching screw 22. The first attaching screw 22 includes a (first) cylindrical section 23 having a diameter A1 and a (first) male screw 24 projecting from the first cylindrical section 23. FIG. 15 is a side view of the second attaching screw 25. The second attaching screw 25 includes a (second) cylindrical section 26 having a diameter A2 and a (second) male screw 27 protecting from the second cylindrical section 26.
Returning to FIG. 16, the first attaching screw 22 is inserted into the through-hole 4 of the substrate 1, so that the first male screw 24 is engaged with the first female screw 8 of the rotation head cylinder 2. A coil spring 14a, interposed between a head of the first attaching screw 22 and the substrate 1, loads the first attaching screw 22 in such a direction as to pressure-contact the rotation head cylinder 2 to the substrate 1. Likewise, the second attaching screw 25 is inserted into the through-hole 5 of the substrate 1, so that the second male screw 27 is engaged with the second female screw 9 of the rotation head cylinder 2. A coil spring 14b, interposed between a head of the second attaching screw 25 and the substrate 1, loads the second attaching screw 25 in such a direction as to pressure-contact the rotation cylinder 2 to the substrate 1.
FIG. 17 is a cross-sectional view of the conventional magnetic recording and reproduction apparatus 100 taken along line Ixe2x80x94I in FIG. 11. The first positioning pin 6 is engaged with the first positioning hole 10, and the second positioning pin 7 is engaged with the second positioning hole 11. In general, relationships of the sizes of the pins, screws and holes are set as follows.
0.0002 mm less than E1-D1 less than 0.1 mm
0.0002 mm less than E2-D2 less than 0.1 mm
0.1 mmxe2x89xa6C1-A1
0.1 mmxe2x89xa6C2-A2
Therefore, the positioning precision of the rotation head cylinder 2 on the substrate 1 required for reliable operation of the conventional magnetic recording and reproduction apparatus is determined by the relationship in size between the first positioning pin 6 and the first positioning hole 10, and the relationship in size between the second positioning pin 7 and the second positioning hole 11. The first cylindrical section 23 and the first through-hole 4 have a gap therebetween, and the second cylindrical section 25 and the second through-hole 5 have a gap therebetween. Therefore, the first and second attaching screws 22 and 25 and the first and second through-holes 4 and 5 do not influence the positioning precision.
As described above, the conventional magnetic recording and reproduction apparatus 100 requires two positioning pins 6 and 7 in correspondence with two positioning holes 10 and 12 in order to provide a positioning precision of the rotation head cylinder 2 to the substrate 1. Such an arrangement undesirably complicates the structure of the magnetic recording and reproduction apparatus. Furthermore, since a large number of elements are required to be precisely positioned relative to each other, there is a high possibility of imprecise positioning of the rotation head cylinder 2.
According to one aspect of the invention, a magnetic recording and reproduction apparatus for recording and reproducing a signal to and from a magnetic tape includes a substrate having a first positioning engagement hole and a second positioning engagement hole; a rotation head cylinder provided on the substrate and having the magnetic tape wound therearound over a prescribed angle, the rotation head cylinder having a first female screw and a second female screw; a first attaching screw having a first cylindrical section for insertion into the first positioning engagement hole and engagement with the first female screw; and a second attaching screw having a second cylindrical section for insertion into the second positioning engagement hole and engagement with the second female screw. The first cylindrical section has a diameter A1, the first positioning engagement hole has a diameter B1, the second cylindrical section has a diameter A2, and the second positioning engagement hole has a width B2, and A1, A2, B1 and B2 fulfill the following relationships:
0.0002 mm less than B1-A1 less than 0.1 mm,
and
0.0002 mm less than B2-A2 less than 0.1 mm.
According to another aspect of the invention, a magnetic recording and reproduction apparatus for recording and reproducing a signal to and from a magnetic tape includes a substrate having a first positioning engagement hole and a second positioning engagement hole; a rotation head cylinder provided on the substrate and having the magnetic tape wound therearound over a prescribed angle, the rotation head cylinder having a first female screw and a second female screw; a first attaching screw having a first male screw for insertion into the first positioning engagement hole and engagement with the first female screw; and a second attaching screw having a second male screw for insertion into the second positioning engagement hole and engagement with the second female screw. The first male screw has a diameter A1, the first positioning engagement hole has a diameter B1, the male screw has a diameter A2, and the second positioning engagement hole has a width B2, and A1, A2, B1 and B2 fulfill the following relationships:
0.0002 mm less than B1-A1 less than 0.1 mm,
and
0.0002 mm less than B2-A2 less than 0.1 mm.
In one embodiment of the invention, one of the first and second positioning engagement holes is circular and the other of the first and second positioning engagement holes is substantially slot-shaped.
In one embodiment of the invention, the magnetic recording and reproduction apparatus further includes a third attaching screw for insertion into a third positioning engagement hole of the substrate.
In one embodiment of the invention, the third attaching screw has a clearance equal to or greater than 0.1 mm when inserted into the third positioning engagement hole.
In one embodiment of the invention, a first coil spring is provided between a head of the first attaching screw and the substrate and a second coil spring is provided between a head of the second attaching screw and the substrate, the first and second coil springs respectively loading the first and second attaching screws in a direction so as to pressure-contact the rotation head cylinder to the substrate.
In one embodiment of the invention, the substrate further has an assembly projection for insertion into an assembly hole of the rotation head cylinder.
In one embodiment of the invention, the assembly projection has a clearance equal to or greater than 0.1 mm when inserted into the assembly hole.
Thus, the invention described herein makes possible the advantages of providing a magnetic recording and reproduction apparatus in which the positioning of a rotation head cylinder on a substrate is achieved with a sufficiently high level of precision while providing a simple structure.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.